Expansive soil improver and improvement method

The invention relates to an expansive soil improver and an improvement method. The expansive soil improver comprises a polycarbonate resin-based suspension, a polyurethane adhesive and hydrophobic magnetic ionic liquid. The expansive soil improver comprises polypropylene fibers, bagasse ash and hydrophobic magnetic ionic liquid. According to the expansive soil improvement method, expansion and shrinkage grades are divided according to the actual situation of expansive soil, and then the improvement mode is determined. The improvement method comprises the following steps: (a) spraying the expansive soil improver; (b) laying a surface improvement layer; and (c) paving a surface improvement layer and spraying an expansive soil improver in a deep layer. By adopting the method, the expansion and shrinkage of the expansive soil can be permanently and remarkably inhibited, and the shear strength is improved; and the used raw materials come from recycled materials, so that waste reutilization is realized, and the env